A laser beam profiler (also termed simply a “laser profiler”) captures and determines the spatial intensity (three dimensional) profile of a fan or “curtain” of a laser beam at a particular plane transverse to the beam propagation path. In a conventional arrangement, a single camera captures the profile of the beam on the object surface. The camera typically resides above the surface plane and the camera lens axis resides at an acute angle (i.e. off-axis) relative to the plane so as to capture the deviation of the laser line upon the surface. This deviation represents the profile of the surface. Laser profilers are useful in a wide range of inspection and manufacturing operations where the user desires to measure and characterize surface details of a planar object via triangulation. One example is the inspection of keyboards in which the profiling task determines whether all keys are at a similar height. One form of laser profiler uses a vision system camera having an image sensor (or “imager”) that can be based upon a CCD or CMOS design. The imager defines a predetermined field of grayscale or color-sensing pixels on an image plane that receive focused light from an imaged scene through a lens. In a typical arrangement, the profiler uses a particular lens assembly that directs reflected laser light from the planar scene to the sensor at an acute angle with respect to the camera sensor's optical axis (which is perpendicular to the image plane). In this manner, the non-perpendicular angle between the laser axis, lens axis and sensor's image plane can fulfill the so-called Scheimpflug principle so as to define a sharp image of the laser line at every measurement distance (described further below). That is, normally when a camera axis is directed at a non-perpendicular angle to a planar scene, only a small crossing width of the overall height of the acquired image is in sharp focus and the focus fades above and below this region.
Undesirably, conventional three-dimensional (3D) laser capture/profile systems generally suffer from a shadow effect, in which portions of the laser beam blocked by the target object result in blank zones in the resulting imaged 3D model of the object. This shadow effect can occur in a relatively deep vertical groove, or other similar surface feature—for example the teeth of a gear. Noise can also exist in various regions of an image, including those adjacent to the transition from a shadow area of the line. It is, thus, desirable to provide a 3D laser capture system that avoids this shadow effect. This arrangement should also desirably be straightforward to use and maintain, and relatively free of potential inaccuracy.